Continuous Glucose Monitoring (CGM) has become an essential tool for managing diabetes, particularly for individuals with type 1 diabetes (T1D). One critical metric derived from CGM data is Time-in-Range (TIR), which reflects the percentage of time a person’s glucose levels remain within a target range. Research indicates that maintaining a TIR greater than 70% is associated with lower HbA1c levels, a key indicator of long-term glucose control.
However, the reliability of TIR as a metric may be influenced by the duration for which the CGM sensor is worn. This study, published in the Journal of Diabetes and Its Complications, investigates the relationship between TIR and HbA1c in youth with T1D, specifically comparing those with sufficient CGM wear-time (≥70%) to those with lower wear-time (<70%).
Methodology
The study involved 60 youth diagnosed with T1D. Participants were categorized based on their CGM wear-time, with one group wearing the device for 70% or more of the time, and the other group wearing it for less than 70%. The researchers calculated Pearson correlations between TIR and HbA1c for each group and compared these correlations using a Fisher r-to-z transformation.
Results
The findings revealed significant correlations between TIR and HbA1c in both groups. For the group with ≥70% wear-time, the correlation coefficient was -0.800 (p < .001), indicating a strong inverse relationship; as TIR increased, HbA1c levels decreased. Conversely, the group with <70% wear-time showed a weaker correlation of -0.404 (p < .001). Notably, the difference in correlation strength between the two groups was statistically significant (z = 3.15, p = .0016).
Conclusion
These results suggest that while the association between TIR and HbA1c is weaker in individuals with less than 70% CGM wear-time, it remains statistically significant. This finding indicates that even when CGM data is limited, it may still provide valuable insights into glycemic control.
What this study does not show
This study does not establish a causal relationship between CGM wear-time and improvements in HbA1c levels, nor does it address the long-term implications of varying wear-time on diabetes management.
Evidence scorecard
- Analytic validity: Established
- Clinical validity: Established
- Clinical utility: Partial
The evidence is based on primary research involving human subjects.